U.S. Pat. No. 6,446,761 B1 describes an elevator system in which data are wirelessly transmitted between an elevator control, an elevator car, a counterweight, and a plurality of elevator operating units that are arranged on the floors. For this purpose, mounted on the said elevator components are terminals with transmitter-receiver units, which have a relatively short range. For the purpose of transmitting data between transmitter-receiver units of elevator components, whose distance from each other is greater than the range, the data are transmitted from the transmitting transmitter-receiver unit to the receiving transmitter-receiver unit via intermediately arranged transmitter-receiver units. For communication with the elevator car that is moving in the elevator hoistway, in each case, depending on the known elevator position, a transmitter-receiver unit that is momentarily near to the elevator car is selected as intermediate station.
US2006/0108181A1 describes an elevator system with an elevator control and an elevator control unit on each floor and in the elevator car. The elevator control units and also the elevator control are equipped with a Piconet module, the Piconet modules forming a wireless communication network through which each Piconet module can receive information that is transmitted from all other Piconet modules and transmit it to all others. The communication network enables the transmission of information over a series of several Piconet modules, which means over distances that exceed the range of a single Piconet module. The Piconet communication module also makes it possible for passengers, by means of a remote-control device with Piconet network, to enter a car call, and for a maintenance specialist, for example, by means of a personal digital assistant (PDA) with special module, to test and influence the elevator control by remote control.
US2012/0175196A1 describes a method for remote access to a plurality of subsystems of an elevator control system. The method comprises, in particular, method steps which, at the beginning of a remote access, serve to detect whether a service device is locally already connected with the elevator control and active.
EP 1415947 A1 discloses a device for the remote maintenance and monitoring of an elevator system with at least one input for the detection of first signals from an elevator control, and/or from a sensor with at least one output of second signals to a telecommunication network, and with at least one processor and a data storage, wherein, stored in the data storage, is a set of remote-maintenance functions, and wherein one of these remote-maintenance functions can be activated. Data from a sensor, or from the elevator control, are permanently transmitted through the telecommunication network to a service center.
EP 1282578 B1 describes a possibility for operating an elevator by means of a radio-telephone as operating unit. Therein, the radio-telephone, which is also referred to as a mobile phone or communication end-device, contains a keypad, which is intended as data-input unit, and a display element, also referred to as a display, which is intended as data-output unit. The mobile phone can communicate wirelessly with a mobile-communication network, wherein speech and/or data can be transmitted. For the purpose of transmitting speech and/or data, the mobile-communication network can enter into communication with further mobile telephones or with a terminal. The terminal consists of a computer system, referred to as a server, which has access to a memory with elevator-specific and/or general information. By means of an interface, the server is also connected with the elevator system. Mobile phone, mobile-communication network, and terminal form a human/machine interface between the user and the elevator system.
A disadvantage of such a method is that, for the wireless communication between a communication unit that is arranged on, or in, the elevator car of the elevator system, and a base station of the public mobile-communication network, a large communication range and a high antenna power are necessary, in order that a certain communication can be assured. On the one hand, this results in a relatively high energy consumption, and on the other hand, there is a substantial risk that the functioning of electronic instruments of the elevator system is impaired by electromagnetic fields. Frequently, complex network protocols are used which, because of safety requirements, generate a high traffic load when transmitting data. Although, by this means, a certain and reliable connection can be established, and a dependable delivery of data packets, and the assurance of an error-free transmission between the units that are involved in the communication, can be guaranteed, on account of such network protocols the (communication) units additionally have a high energy consumption.